Field of the Invention
The present invention relates to wireless communication, and more particularly to a method and an apparatus for protecting a TXOP in a wireless communication system.
Related Art
Wi-Fi is a wireless local area network (WLAN) technology that allows a wireless apparatus to access the Internet in a frequency band of 2.4 GHz, 5 GHz, or 60 GHz. The WLAN is based on an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard.
An IEEE 802.11n standard supports multiple antennas and provides maximum 600 Mbit/s data rate. A system that supports IEEE 802.11n is referred to as a high throughput (HT) system.
An IEEE 802.11ac standard operates primarily in the 5 GHz band and provides data rate of 1 Gbit/s or more. The IEEE 802.11ac supports downlink multi-user multiple input multiple output (DL MU-MIMO). A system that supports IEEE 802.11ac is referred to as a very high throughput (VHT) system.
IEEE 802.11ax is developed as next-generation WLAN for coping with higher data rate and a higher user load. A scope of the IEEE 802.11ax may include 1) enhancement of an 802.11 physical (PHY) layer and a medium access control (MAC) layer, 2) enhancement of spectrum efficiency and area throughput, 3) performance enhancement in an environment in which an interference source exists, a dense heterogeneous network environment, and an environment in which the high user load exists, and the like.
As described above, various channel bandwidths are available from 20 MHz to 160 MHz in a WLAN system. Accordingly, determination of Wi-Fi performance is an important factor to determine a suitable channel bandwidth for communication between a transmission terminal and a reception terminal.
In order to determine a suitable channel bandwidth for communication between a transmission terminal and a reception terminal, a dynamic channel bandwidth configuration protocol based on a request to send (RTS) frame and a clear to send (CTS) frame is developed from IEEE 802.11ac. An initial RTS frame and an initial CTS frame are created in order to reduce a hidden node issue and a data frame collision overhead. The transmission terminal transmits an RTS frame to the reception terminal before transmitting a data frame. A purpose terminal receiving the RTS frame responds the transmission terminal by the CTS frame. Third terminals receiving the RTS frame and the CTS frame may delay a medium access for a predetermined time to protect a data frame to be next transmitted.
However, since exchange of RTS/CTS frames is achieved by simple transmission or is achieved between an AP and a designated specific STA, the RTS/CTS frame exchange is not suitable in an uplink Multi (MU) user environment.